Unit pixel having light emitting device, pixel module and displaying apparatus

ABSTRACT

A displaying apparatus including a panel substrate and pixel modules arranged thereon, each pixel module including a circuit board and unit pixels on the circuit board, in which each unit pixel includes light emitting devices longitudinally extending along a first direction on the circuit board and including a substrate, a light emitting structure including first and second conductivity type semiconductor layers and an active layer therebetween, a first connection layer electrically connected to the first conductivity type semiconductor layer, a second connection layer electrically connected to the second conductivity type semiconductor layer, a step adjustment layer disposed between the first connection layer and the second connection layer and covering a portion of the light emitting device, in which the light emitting devices in the unit pixel are arranged in a second direction crossing the first direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.17/833,734, filed on Jun. 6, 2022, which is a continuation of U.S.patent application Ser. No. 16/831,973, filed on Mar. 27, 2020, whichclaims the benefit of U.S. Provisional Application No. 62/826,033, filedon Mar. 29, 2019, each of which is hereby incorporated in its entiretyby reference for all purposes as set forth herein.

BACKGROUND Field

Exemplary embodiments relate to a displaying apparatus, and moreparticularly, to a unit pixel having a light emitting device, a pixelmodule having the same, and a displaying apparatus having the same.

Discussion of the Background

Light emitting devices are semiconductor devices using light emittingdiodes, which are inorganic light sources, and are used in varioustechnical fields, such as displaying apparatuses, automobile lamps,general lighting, and the like. Light emitting diodes have advantagessuch as longer lifespan, lower power consumption, and fast response thanexisting light sources, and thus, light emitting diodes have beenreplacing the existing light sources.

The conventional light emitting diodes have been generally used asbacklight light sources in display apparatuses. However, displayingapparatuses that directly realize images using the light emitting diodeshave been recently developed. Such displays are also referred to asmicro LED displays.

In general, a displaying apparatus displays various colors throughmixture of blue, green, and red light. In order to realize variousimages, the displaying apparatus includes a plurality of pixels, eachincluding sub-pixels corresponding to one of blue, green, and red light.As such, a color of a certain pixel is typically determined based on thecolors of the sub-pixels, so that images can be realized through thecombination of such pixels.

In the case of the micro LED display, a micro LED is arranged on atwo-dimensional plane corresponding to each sub-pixel, and, accordingly,a large number of micro LEDs need to be arranged on a single substrate.However, the micro LED is extremely small, for example, 200 μm or less,further 100 μm or less, and these small sizes cause various problems. Inparticular, it is difficult to handle the light emitting diodes havingsmall sizes, and thus, it is not easy to directly mount the lightemitting diodes on a display panel.

The above information disclosed in this Background section is only forunderstanding of the background of the inventive concepts, and,therefore, it may contain information that does not constitute priorart.

SUMMARY

Unit pixels constructed according to exemplary embodiments of theinvention are capable of being mounted on a circuit board, and a displayapparatus having the same.

Exemplary embodiments provide a unit pixel that has high reliability anda displaying apparatus having the same.

Exemplary embodiments also provide a unit pixel that prevents a failedlight emitting device from being mounted and a displaying apparatushaving the same.

Additional features of the inventive concepts will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the inventive concepts.

A unit pixel according to an exemplary embodiment includes: atransparent substrate; a plurality of light emitting devices arranged onthe transparent substrate; an adhesive layer bonding the light emittingdevices to the transparent substrate; a step adjusting layer coveringthe light emitting device and bonded to the adhesive layer; connectionlayers disposed on the step adjustment layer, and electrically connectedto the light emitting devices, in which the step adjustment layer has aconcave-convex pattern along an edge thereof.

A unit pixel according to another exemplary embodiment includes: atransparent substrate; at least three light emitting devices arranged onthe transparent substrate and emitting light of different colors; anadhesive layer bonding the light emitting devices to the transparentsubstrate; a step adjusting layer covering the light emitting device andbonded to the adhesive layer; connection layers disposed on the stepadjustment layer, and electrically connected to the light emittingdevices, in which the at least three light emitting devices are arrangedin a line.

A pixel module according to another exemplary embodiment includes: acircuit board; a plurality of unit pixels disposed on the circuit board;and a cover layer covering the plurality of unit pixels, each of theunit pixels including: a transparent substrate; a plurality of lightemitting devices arranged on the transparent substrate; an adhesivelayer bonding the light emitting devices to the transparent substrate; astep adjusting layer covering the light emitting device and bonded tothe adhesive layer; connection layers disposed on the step adjustmentlayer, and electrically connected to the light emitting devices, inwhich the step adjustment layer has a concave-convex pattern along anedge thereof.

A displaying apparatus according to another exemplary embodimentincludes: a panel substrate; and a plurality of pixel modules arrangedon the panel substrate, each of the pixel modules including: a circuitboard; a plurality of unit pixels disposed on the circuit board; and acover layer covering the plurality of unit pixels, in which each of theunit pixels includes: a transparent substrate; a plurality of lightemitting devices arranged on the transparent substrate; an adhesivelayer bonding the light emitting devices to the transparent substrate; astep adjusting layer covering the light emitting device and bonded tothe adhesive layer; connection layers disposed on the step adjustmentlayer, and electrically connected to the light emitting devices, and thestep adjustment layer has a concave-convex pattern along an edgethereof.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of theinvention, and together with the description serve to explain theinventive concepts.

FIG. 1 is a schematic plan view illustrating a displaying apparatusaccording to an exemplary embodiment.

FIG. 2A is a schematic plan view illustrating a light emitting deviceaccording to an exemplary embodiment.

FIG. 2B is a schematic cross-sectional view taken along line A-A of FIG.2A.

FIG. 3A is a schematic plan view illustrating a unit pixel according toan exemplary embodiment.

FIG. 3B is a schematic cross-sectional view taken along line B-B of FIG.3A.

FIG. 4A is a schematic plan view illustrating a pixel module accordingto an exemplary embodiment.

FIG. 4B is a schematic cross-sectional view taken along line C-C of FIG.4A.

FIG. 4C is a schematic rear view illustrating a pixel module accordingto an exemplary embodiment.

FIG. 4D is a schematic circuit diagram illustrating a pixel moduleaccording to an exemplary embodiment.

FIG. 4E is a schematic circuit diagram illustrating a pixel moduleaccording to another exemplary embodiment.

FIG. 5A, FIG. 5B, and FIG. 5C are schematic plan views illustrating aunit pixel according to exemplary embodiments.

FIGS. 6A, 6B, 6C, 6D, 6E, 6F, 6G, 6H, 6I, 6J, and 6K are schematiccross-sectional views illustrating a method of transferring lightemitting devices according to an exemplary embodiment.

FIGS. 7A, 7B, 7C, 7D, 7E, 7F, 7G, 7H, 7I, 7J, 7K, and 7L are schematiccross-sectional views illustrating a method of transferring lightemitting devices according to another exemplary embodiment.

FIGS. 8A, 8B, 8C, 8D, 8E, 8F, 8G, 8H, 8I, 8J, and 8K are schematiccross-sectional views illustrating a method of transferring lightemitting devices according to another exemplary embodiment.

FIGS. 9A, 9B, 9C, 9D, 9E, 9F, 9G, 9H, 9I, 9J, 9K, 9L, 9M, 9N, and 9O areschematic plan views illustrating a light emitting device according toexemplary embodiments.

FIG. 10 is a schematic cross-sectional view illustrating a unit pixelaccording to another exemplary embodiment.

FIG. 11 is a schematic cross-sectional view illustrating a pixel moduleaccording to another exemplary embodiment.

DETAILED DESCRIPTION

In the following description, for the purposes of explanation, numerousspecific details are set forth in order to provide a thoroughunderstanding of various exemplary embodiments or implementations of theinvention. As used herein “embodiments” and “implementations” areinterchangeable words that are non-limiting examples of devices ormethods employing one or more of the inventive concepts disclosedherein. It is apparent, however, that various exemplary embodiments maybe practiced without these specific details or with one or moreequivalent arrangements. In other instances, well-known structures anddevices are shown in block diagram form in order to avoid unnecessarilyobscuring various exemplary embodiments. Further, various exemplaryembodiments may be different, but do not have to be exclusive. Forexample, specific shapes, configurations, and characteristics of anexemplary embodiment may be used or implemented in another exemplaryembodiment without departing from the inventive concepts.

Unless otherwise specified, the illustrated exemplary embodiments are tobe understood as providing exemplary features of varying detail of someways in which the inventive concepts may be implemented in practice.Therefore, unless otherwise specified, the features, components,modules, layers, films, panels, regions, and/or aspects, etc.(hereinafter individually or collectively referred to as “elements”), ofthe various embodiments may be otherwise combined, separated,interchanged, and/or rearranged without departing from the inventiveconcepts.

The use of cross-hatching and/or shading in the accompanying drawings isgenerally provided to clarify boundaries between adjacent elements. Assuch, neither the presence nor the absence of cross-hatching or shadingconveys or indicates any preference or requirement for particularmaterials, material properties, dimensions, proportions, commonalitiesbetween illustrated elements, and/or any other characteristic,attribute, property, etc., of the elements, unless specified. Further,in the accompanying drawings, the size and relative sizes of elementsmay be exaggerated for clarity and/or descriptive purposes. When anexemplary embodiment may be implemented differently, a specific processorder may be performed differently from the described order. Forexample, two consecutively described processes may be performedsubstantially at the same time or performed in an order opposite to thedescribed order. Also, like reference numerals denote like elements.

When an element, such as a layer, is referred to as being “on,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, connected to, or coupled to the other element or layer orintervening elements or layers may be present. When, however, an elementor layer is referred to as being “directly on,” “directly connected to,”or “directly coupled to” another element or layer, there are nointervening elements or layers present. To this end, the term“connected” may refer to physical, electrical, and/or fluid connection,with or without intervening elements. Further, the D1-axis, the D2-axis,and the D3-axis are not limited to three axes of a rectangularcoordinate system, such as the x, y, and z-axes, and may be interpretedin a broader sense. For example, the D1-axis, the D2-axis, and theD3-axis may be perpendicular to one another, or may represent differentdirections that are not perpendicular to one another. For the purposesof this disclosure, “at least one of X, Y, and Z” and “at least oneselected from the group consisting of X, Y, and Z” may be construed as Xonly, Y only, Z only, or any combination of two or more of X, Y, and Z,such as, for instance, XYZ, XYY, YZ, and ZZ. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

Although the terms “first,” “second,” etc. may be used herein todescribe various types of elements, these elements should not be limitedby these terms. These terms are used to distinguish one element fromanother element. Thus, a first element discussed below could be termed asecond element without departing from the teachings of the disclosure.

Spatially relative terms, such as “beneath,” “below,” “under,” “lower,”“above,” “upper,” “over,” “higher,” “side” (e.g., as in “sidewall”), andthe like, may be used herein for descriptive purposes, and, thereby, todescribe one elements relationship to another element(s) as illustratedin the drawings. Spatially relative terms are intended to encompassdifferent orientations of an apparatus in use, operation, and/ormanufacture in addition to the orientation depicted in the drawings. Forexample, if the apparatus in the drawings is turned over, elementsdescribed as “below” or “beneath” other elements or features would thenbe oriented “above” the other elements or features. Thus, the exemplaryterm “below” can encompass both an orientation of above and below.Furthermore, the apparatus may be otherwise oriented (e.g., rotated 90degrees or at other orientations), and, as such, the spatially relativedescriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particularembodiments and is not intended to be limiting. As used herein, thesingular forms, “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. Moreover,the terms “comprises,” “comprising,” “includes,” and/or “including,”when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, components, and/orgroups thereof, but do not preclude the presence or addition of one ormore other features, integers, steps, operations, elements, components,and/or groups thereof. It is also noted that, as used herein, the terms“substantially,” “about,” and other similar terms, are used as terms ofapproximation and not as terms of degree, and, as such, are utilized toaccount for inherent deviations in measured, calculated, and/or providedvalues that would be recognized by one of ordinary skill in the art.

Various exemplary embodiments are described herein with reference tosectional and/or exploded illustrations that are schematic illustrationsof idealized exemplary embodiments and/or intermediate structures. Assuch, variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should notnecessarily be construed as limited to the particular illustrated shapesof regions, but are to include deviations in shapes that result from,for instance, manufacturing. In this manner, regions illustrated in thedrawings may be schematic in nature and the shapes of these regions maynot reflect actual shapes of regions of a device and, as such, are notnecessarily intended to be limiting.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure is a part. Terms,such as those defined in commonly used dictionaries, should beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art and should not be interpreted in anidealized or overly formal sense, unless expressly so defined herein.

A unit pixel according to an exemplary embodiment includes: atransparent substrate; a plurality of light emitting devices arranged onthe transparent substrate; an adhesive layer bonding the light emittingdevices to the transparent substrate; a step adjusting layer coveringthe light emitting device and bonded to the adhesive layer; connectionlayers disposed on the step adjustment layer, and electrically connectedto the light emitting devices, in which the step adjustment layer has aconcave-convex pattern along an edge thereof.

The plurality of light emitting devices may include at least three lightemitting devices emitting light of different colors, and the at leastthree light emitting devices may be arranged in a line.

The plurality of light emitting devices may further include lightemitting devices emitting red, green, and blue light.

Each of the light emitting devices may include a light emittingstructure including a first conductivity type semiconductor layer, asecond conductivity type semiconductor layer and an active layerinterposed between the first and second conductivity type semiconductorlayers; and a first electrode pad and a second electrode pad disposed onthe light emitting structure, in which the step adjustment layer mayhave openings exposing the first and second electrode pads, and theconnection layers may be electrically connected to the first and secondelectrode pads through the openings of the step adjustment layer.

Each of the light emitting devices may include a plurality of connectiontips.

Connection tips of any one of the light emitting devices may be arrangedat different locations from those of connection tips of remaining lightemitting devices.

The plurality of connection tips arranged on each light emitting devicemay be disposed to be asymmetrical with respect to at least onearrangement direction.

The unit pixel may further include a light blocking layer disposedbetween the adhesive layer and the transparent substrate, and the lightblocking layer may have a window that transmits light generated in thelight emitting device.

A width of the window may be smaller than that of the light emittingdevice according to an exemplary embodiment. The width of the window maybe wider than that of the light emitting device according to anotherexemplary embodiment.

The unit pixel may further include a protection layer covering the stepadjustment layer and the contact layers, and the protection layer mayhave openings located on the contact layers.

The unit pixel may further include bumps disposed in openings of theprotection layer, and the bumps may be electrically connected to thecontact layers, respectively.

A unit pixel according to another exemplary embodiment includes: atransparent substrate; at least three light emitting devices arranged onthe transparent substrate, and emitting light of different colors; anadhesive layer bonding the light emitting devices to the transparentsubstrate; a step adjusting layer covering the light emitting device andbonded to the adhesive layer; connection layers disposed on the stepadjustment layer, and electrically connected to the light emittingdevices, in which the at least three light emitting devices are arrangedin a line.

The transparent substrate may be a sapphire substrate.

A pixel module according to an exemplary embodiment includes: a circuitboard; a plurality of unit pixels disposed on the circuit board; and acover layer covering the plurality of unit pixels, each of the unitpixels including: a transparent substrate; a plurality of light emittingdevices arranged on the transparent substrate; an adhesive layer bondingthe light emitting devices to the transparent substrate; a stepadjusting layer covering the light emitting device and bonded to theadhesive layer; connection layers disposed on the step adjustment layer,and electrically connected to the light emitting devices, in which thestep adjustment layer has a concave-convex pattern along an edgethereof.

The unit pixel may further include a protection layer covering the stepadjustment layer and the contact layers, and the protection layer mayhave openings located on the contact layers.

The pixel module, according to an exemplary embodiment, may furtherinclude a bonding material bonding the light emitting devices and thecircuit board, and the bonding material may fill at least a portion ofthe openings of the protection layer.

The pixel module, according to another exemplary embodiment, may furtherinclude a bonding material bonding the light emitting devices and thecircuit board, in which the unit pixel may further include bumpsdisposed in the openings of the protection layer, the circuit board mayinclude pads exposed on an upper surface thereof, and the bondingmaterial may bond the bumps with the pads.

The circuit board may further include bottom pads disposed on a bottomthereof, and the number of the bottom pads may be smaller than that ofthe pads. For example, the number of the bottom pads may be ½ of thenumber of the pads.

The plurality of light emitting devices may include at least three lightemitting devices emitting light of different colors, and the at leastthree light emitting devices may be arranged in a line.

A displaying apparatus according to an exemplary embodiment includes: apanel substrate; and a plurality of pixel modules arranged on the panelsubstrate, each of the pixel modules including: a circuit board; aplurality of unit pixels disposed on the circuit board; and a coverlayer covering the plurality of unit pixels, in which each of the unitpixels includes: a transparent substrate; a plurality of light emittingdevices arranged on the transparent substrate; an adhesive layer bondingthe light emitting devices to the transparent substrate; a stepadjusting layer covering the light emitting device and bonded to theadhesive layer; connection layers disposed on the step adjustment layer,and electrically connected to the light emitting devices, in which thestep adjustment layer has a concave-convex pattern along an edgethereof.

Hereinafter, exemplary embodiments will be described in detail withreference to the accompanying drawings.

FIG. 1 is a schematic plan view illustrating a displaying apparatusaccording to an exemplary embodiment.

Referring to FIG. 1 , a displaying apparatus 10000 includes a panelsubstrate 2100 and a plurality of pixel modules 1000.

The panel substrate 2100 may include a circuit for a passive matrixdriving or active matrix driving manner. In an exemplary embodiment, thepanel substrate 2100 may include wirings and resistors therein, and, inanother exemplary embodiment, the panel substrate 2100 may includewirings, transistors, and capacitors. The panel substrate 2100 may alsohave pads disposed on at least one surface thereof for electricalconnection to the circuit.

A plurality of pixel modules 1000 is arranged on the panel substrate2100. Each pixel module 1000 may include a circuit board 1001 (see alsoFIG. 4A), and a plurality of unit pixels 100 disposed on the circuitboard 1001.

Each unit pixel 100 includes a plurality of light emitting devices 10.The light emitting devices 10 may include light emitting devices 10 a,10 b, and 10 c that emit light having different colors. The lightemitting devices 10 a, 10 b, and 10 c in each unit pixel 100 may bearranged in a line as shown in FIG. 1 . In particular, the lightemitting devices 10 a, 10 b, and 10 c may be arranged in a verticaldirection with respect to a display screen, on which the image isdisplayed.

Hereinafter, each element of the displaying apparatus 10000 will bedescribed in more detail in the order of the light emitting device 10,the unit pixel 100, and the pixel module 1000 that are disposed in thedisplaying apparatus 10000.

FIG. 2A is a schematic plan view illustrating a light emitting deviceaccording to an exemplary embodiment, and FIG. 2B is a schematiccross-sectional view taken along line A-A of FIG. 2A. Hereinafter,although the light emitting device shown in FIGS. 2A and 2B will bedescribed with reference to the light emitting device 10 a, the lightemitting devices 10 b and 10 c according to an exemplary embodiment mayhave substantially the same structure as the light emitting device 10 ashown in FIGS. 2A and 2B.

Referring to FIG. 2A and FIG. 2B, the light emitting devices 10 aincludes a light emitting structure including a first conductivity typesemiconductor layer 21, an active layer 23, and a second conductivitytype semiconductor layer 25. In addition, the light emitting device 10 amay include an ohmic contact layer 27, an insulation layer 29, a firstelectrode pad 31, and a second electrode pad 33. Connection tips 55 bmay be disposed on a side of the first conductivity type semiconductorlayer 21 that opposes a side on which the first electrode pad 33 and thesecond electrode pad 33 are disposed.

The light emitting structure including the first conductivity typesemiconductor layer 21, the active layer 23, and the second conductivitytype semiconductor layer 25 may be grown on a substrate. The substratemay be one of various substrates that may grow semiconductors thereon,such as gallium nitride substrate, GaAs substrate, Si substrate, andsapphire substrate, especially patterned sapphire substrate. The growthsubstrate may be separated from the semiconductor layers using aprocess, such as a mechanical grinding, a laser lift off, a chemicallift off process, or the like. However, the inventive concepts are notlimited thereto, and, in some exemplary embodiments, a portion of thesubstrate may be retained to be disposed on the first conductivity typesemiconductor layer 21.

When the light emitting device 10 a emits red light according to anexemplary embodiment, the semiconductor layers may include aluminumgallium arsenide (AlGaAs), gallium arsenide phosphide (GaAsP), aluminumgallium indium phosphide (AlGaInP), or gallium phosphide (GaP).

When the light emitting device 10 b emits green light according to anexemplary embodiment, the semiconductor layers may include indiumgallium nitride (InGaN), gallium nitride (GaN), gallium phosphide (GaP),aluminum gallium indium phosphide (AlGaInP), or aluminum galliumphosphide. (AlGaP).

When the light emitting device 10 c emits blue light according to anexemplary embodiment, the semiconductor layers may include galliumnitride (GaN), indium gallium nitride (InGaN), or zinc selenide (ZnSe).

The first conductivity type and the second conductivity type may haveopposite polarities. For example, when the first conductivity type is ann-type, the second conductivity type may be a p-type, and, when thesecond conductivity type is a p-type, the second conductivity type maybe an n-type.

The first conductivity type semiconductor layer 21, the active layer 23,and the second conductivity type semiconductor layer 25 may be grown onthe substrate in a chamber using a known process, such as metal organicchemical vapor deposition (MOCVD) process. In addition, the firstconductivity type semiconductor layer 21 may include n-type impurities(e.g., Si, Ge, and Sn), and the second conductivity type semiconductorlayer 25 may include p-type impurities (e.g., Mg, Sr, and Ba). In anexemplary embodiment, the first conductivity type semiconductor layer 21may include GaN or AlGaN containing Si as a dopant, and the secondconductivity type semiconductor layer 25 may include GaN or AlGaNcontaining Mg as a dopant.

Although the first conductivity type semiconductor layer 21 and thesecond conductivity type semiconductor layer 25 are shown as singlelayers in the drawings, these layers may be multiple layers, and mayalso include a superlattice layer. The active layer 23 may include asingle quantum well structure or a multiple quantum well structure, anda composition ratio of a nitride-based semiconductor may be adjusted toemit a desired wavelength. For example, the active layer 23 may emitblue light, green light, red light, or ultraviolet light.

The second conductivity type semiconductor layer 25 and the active layer23 may have a mesa M structure, and may be disposed on the firstconductivity type semiconductor layer 21. The mesa M may include thesecond conductivity type semiconductor layer 25 and the active layer 23,and may include a portion of the first conductivity type semiconductorlayer 21 as shown in FIG. 2B. The mesa M may be disposed on the portionof the first conductivity type semiconductor layer 21, and an uppersurface of the first conductivity type semiconductor layer 21 may beexposed around the mesa M.

The first conductivity type semiconductor layer 21 may have aconcave-convex pattern from surface texturing. Surface texturing may beperformed by patterning, for example, using a dry etching process. Forexample, cone-shaped protrusions each having an elevation of about 2.5μm to about 3 μm may be formed. A distance between the cones may beabout 1.5 μm to about 2 μm, and a diameter of a bottom of the cone maybe about 3 μm. Color difference may be reduced by forming theconcave-convex pattern on the surface of the first conductivity typesemiconductor layer 21. Surface texturing may be performed on the firstconductivity type semiconductor layers in each of the first, second, andthird light emitting devices 10 a, 10 b, and 10 c, but the inventiveconcepts are not limited thereto. In some exemplary embodiments, surfacetexturing may not be performed in some of the light emitting devices.

When the first, second, and third light emitting devices 10 a, 10 b, and10 c are arranged in a line in a unit pixel 100 which will be describedlater, color difference between the left and right of a pixel may bereduced by including the surface-textured first conductivity typesemiconductor layer 21.

The mesa M may have a through hole 25 a exposing the first conductivitytype semiconductor layer 21. The through hole 25 a may be disposed closeto one edge of the mesa M, without being limited thereto. In someexemplary embodiments, the through hole 25 a may be disposed at a centerof the mesa M.

The ohmic contact layer 27 is disposed on the second conductivity typesemiconductor layer 25 to be in ohmic contact with the secondconductivity type semiconductor layer 25. The ohmic contact layer 27 maybe formed of a single layer or multiple layers, and may be formed of atransparent conductive oxide film or a metal film. For example, thetransparent conductive oxide film may include ITO, ZnO, or the like, andthe metal film may include metal, such as Al, Ti, Cr, Ni, Au, or thelike and an alloy thereof.

The insulation layer 29 covers the mesa M and the ohmic contact layer27. The insulation layer 29 may further cover upper and side surfaces ofthe first conductivity type semiconductor layer 21 exposed around themesa M. The insulation layer 29 may have an opening 29 a exposing theohmic contact layer 27, and an opening 29 b exposing the firstconductivity type semiconductor layer 21 in the through hole 25 a. Theinsulation layer 29 may be formed of a single layer or multiple layersof a silicon oxide film or a silicon nitride film. The insulation layer29 may also include an insulation reflector, such as a distributed Braggreflector.

The first electrode pad 31 and the second electrode pad 33 are disposedon the insulation layer 29. The second electrode pad 33 may beelectrically connected to the ohmic contact layer 27 through the opening29 a, and the first electrode pad 31 may be electrically connected tothe first conductivity type semiconductor layer 21 through the opening29 b.

The first and/or second electrode pads 31 and 33 may be formed of asingle layer or a multiple layer of metal. As a material of the firstand/or second electrode pads 31 and 33, metal such as Al, Ti, Cr, Ni,Au, or the like and an alloy thereof may be used.

The connection tips 55 b may be formed on the light emitting device 10a. As shown in FIG. 2A, four connection tips 55 b may be disposed on thelight emitting structure.

For example, one connection tip 55 b may be disposed at approximately acenter of the light emitting device 10 a, two connection tips 55 b maybe disposed at a location overlapping with the second electrode pad 33,and one connection tip 55 b may be disposed at a location overlappingwith the first electrode pad 31. Three connection tips 55 b may bedisposed in substantially a triangular shape near outline of the lightemitting device 10 a, and one connection tip 55 b disposed at the centerof the light emitting device 10 a may be located in the triangle formedby the three connection tips 55 b.

The two connection tips 55 b disposed at the location overlapping withthe second electrode pad 33 may be disposed near one edge of the secondelectrode pad 33, and may be disposed to face each other with respect toan elongated straight line passing through the center.

The connection tip 55 b disposed at the location overlapping with thefirst electrode pad 31 may be disposed near one edge of the firstelectrode pad 31, and may be disposed away from the elongated straightline passing through the center.

Each of the connection tips 55 b may have substantially a righttriangular shape, and the connection tip 55 b disposed at the center ofthe light emitting device 10 may be arranged in a direction opposite tothe other connection tips 55 b as shown in the drawing.

When the light emitting devices 10 are separated from a connectionportion using the connection tips 55 b, the connection tip 55 boverlapping with the first electrode pad 31 may be formed first, thenthe connection tip 55 b near the center may be formed, and, finally, theconnection tips 55 b overlapping with the second electrode pad 33 may beformed. As such, the light emitting devices 10 may be easily separatedfrom the connection portion, and cracks which may otherwise occur in thelight emitting devices may be prevented.

When picking up or mounting the light emitting device 10 a, for example,the light emitting device 10 a may be unstably picked up or mounted dueto the location of the connection tips, and thus, cracks may occur. Incontrast, since the connection tips 55 b according to an exemplaryembodiment are arranged on both edges of the light emitting device 10 aand near the center of the light emitting device 10 a, respectively, thelight emitting device 10 a may be picked up or mounted stably andthereby preventing cracks generated in the light emitting device 10 a.

A total area of the four connection tips 55 b may be about 0.8% of aplanar area of the light emitting device 10 a according to the exemplaryembodiment.

Although the locations of the connection tips 55 b have been brieflydescribed with reference to FIG. 2A and FIG. 2B, the inventive conceptsare not limited thereto. In some exemplary embodiments, the connectiontips 55 b may be arranged in various shapes at various locations. Inaddition, the light emitting devices 10 a, 10 b, and 10 c may includethe connection tips 55 b disposed at the same locations, but theinventive concepts are not limited thereto. For example, the connectiontips 55 b disposed on the first light emitting device 10 a may bedisposed at locations different from those disposed on the second andthird light emitting devices 10 b and 10 c. The locations and formationof the connection tips 55 b and a method of transferring the lightemitting devices 10 will be described later.

Although the light emitting device 10 a according to an exemplaryembodiment has been briefly described with reference to the drawings,the light emitting device 10 a may further include a layer havingadditional functions in addition to the above-described layers. Forexample, various layers such as a reflective layer for reflecting light,an additional insulation layer for insulating a specific element, and asolder preventing layer for preventing diffusion of solder may befurther included.

When a flip chip type light emitting device is formed, the mesa may beformed to have various shapes, and the locations and shapes of the firstand second electrode pads 31 and 33 may also be variously modified. Inaddition, the ohmic contact layer 27 may be omitted, and the secondelectrode pad 33 may directly contact the second conductivity typesemiconductor layer 25. Although the first electrode pad 31 is shown asbeing directly connected to the first conductivity type semiconductorlayer 21 in FIG. 2B, in some exemplary embodiments, a contact layer maybe formed first on the first conductivity type semiconductor layer 21exposed to the through hole 25 a, and the first electrode pad 31 may beconnected to the contact layer.

FIG. 3A is a schematic plan view illustrating a unit pixel 100 accordingto an exemplary embodiment, and FIG. 3B is a schematic cross-sectionalview taken along line B-B of FIG. 3A.

Referring to FIG. 3A and FIG. 3B, the unit pixel 100 may include atransparent substrate 121, a first, second, and third light emittingdevices 10 a, 10 b, and 10 c, a light blocking layer 123, and anadhesive layer 125, a step adjustment layer 127, connection layers 129a, 129 b, 129 c, and 129 d, bumps 133 a, 133 b, 133 c, and 133 d, and aprotection layer 131.

The unit pixel 100 provides a single pixel including the first, second,and third light emitting devices 10 a, 10 b, and 10 c. The first,second, and third light emitting devices 10 a, 10 b, and 10 c emit lighthaving different colors, and the first, second, and third light emittingdevices 10 a, 10 b, and 10 c correspond to sub-pixels, respectively.

The transparent substrate 121 is a light transmissive substrate, such asPET, glass substrate, quartz, sapphire substrate, or the like. Thetransparent substrate 121 is disposed on a light emitting surface of thedisplaying apparatus 10000 of FIG. 1 , and light emitted from the lightemitting devices 10 a, 10 b, and 10 c is emitted to the outside throughthe transparent substrate 121. The transparent substrate 121 may includea concave-convex PR on the light emitting surface. Light emissionefficiency may be improved through the concave-convex PR, and moreuniform light may be emitted due to the concave-convex PR. Thetransparent substrate 121 may also include an anti-reflection coating,or may include an antiglare layer, or may be antiglare treated. Thetransparent substrate 121 may have a thickness of, for example, about 50μm to about 500 μm.

Since the transparent substrate 121 is disposed on the light emittingsurface, the transparent substrate 121 may not include a circuit.However, the inventive concepts are not limited thereto, and, in someexemplary embodiments, the transparent substrate 121 may include thecircuit.

Although a single unit pixel 100 is illustrated to be formed on a singletransparent substrate 121, a plurality of unit pixels 1000 may be formedon the single transparent substrate 121.

The light blocking layer 123 may include an absorbing material whichabsorbs light, such as carbon black. The light absorbing material mayprevent light generated in the light emitting devices 10 a, 10 b, and 10c from leaking in a region between the transparent substrate 121 and thelight emitting devices 10 a, 10 b, and 10 c toward a side surfacethereof, and may improve contrast of a displaying apparatus.

The light blocking layer 123 may have a window 123 a providing a routefor light to progress, so that light generated in the light emittingdevices 10 a, 10 b, and 10 c is incident on the transparent substrate121. A width of the window 123 a may be less than that of the lightemitting device, but is not limited thereto. In some exemplaryembodiments, a width of the window 123 a may be greater than or equal tothe width of the light emitting device.

The window 123 a of the light blocking layer 123 also defines anarrangement location of the light emitting devices 10 a, 10 b, and 10 c.As such, separate arrangement markers for defining arrangement locationsof the light emitting devices 10 a, 10 b, and 10 c may be omitted.However, the inventive concepts are not limited thereto, and, in someexemplary embodiments, the arrangement markers may be disposed on thetransparent substrate 121, or on the light blocking layer 123 or theadhesive layer 125, to provide locations to arrange the light emittingdevices 10 a, 10 b, and 10 c.

The adhesive layer 125 is attached onto the transparent substrate 121.The adhesive layer 125 may cover the light blocking layer 123. Theadhesive layer 125 may be attached to an entire surface of thetransparent substrate 121, but is not limited thereto. In some exemplaryembodiments, the adhesive layer 125 may be attached to a portion of thetransparent substrate 121 to expose a region near an edge of thetransparent substrate 121. The adhesive layer 125 is used to attach thelight emitting devices 10 a, 10 b, and 10 c to the transparent substrate121. The adhesive layer 125 may fill the window 123 a formed in thelight blocking layer 123.

The adhesive layer 125 may be formed of a light transmissive layer, andtransmits light emitted from the light emitting devices 10 a, 10 b, and10 c. The adhesive layer 125 may include a diffuser, such as SiO₂, TiO₂,ZnO, or the like to diffuse light. The light diffusing material preventsthe light emitting devices 10 a, 10 b, and 10 c from being observed fromthe light emitting surface.

The first, second, and third light emitting devices 10 a, 10 b, and 10 care disposed on the transparent substrate 121. The first, second, andthird light emitting devices 10 a, 10 b, and 10 c may be attached to thetransparent substrate 121 by the adhesive layer 125. The first, second,and third light emitting devices 10 a, 10 b, and 10 c may be disposed tocorrespond to the windows 123 a of the light blocking layer 123. Whenthe light blocking layer 123 is omitted, the arrangement markers may beadded to provide the arrangement locations of the light emitting devices10 a, 10 b, and 10 c.

The first, second, and third light emitting devices 10 a, 10 b, and 10 cmay be, for example, green light emitting devices, red light emittingdevices, and blue light emitting devices, respectively. Since specificconfigurations of each of the first, second, and third light emittingdevices 10 a, 10 b, and 10 c are substantially the same as thosedescribed with reference to FIG. 2A and FIG. 2B, repeated descriptionsthereof will be omitted.

The first, second, and third light emitting devices 10 a, 10 b, and 10 cmay be arranged in a line, as shown in FIG. 3A. In particular, when thetransparent substrate 121 is a sapphire substrate, the sapphiresubstrate may include clean-cut surfaces (e.g., m-plane) and nonclean-cut surfaces (e.g., a-plane) due to a location of a crystal planealong a cutting direction. For example, when the sapphire substrate iscut into a quadrangular shape, two cutting planes on both sides thereof(e.g., m-plane) may be cut cleanly along the crystal plane, and tworemaining cutting planes (e.g., a-plane) disposed in a directionperpendicular to the cutting planes may not cut cleanly. In this case,the clean-cut surfaces of the sapphire substrate 121 may besubstantially flush with an arrangement direction of the light emittingdevices 10 a, 10 b, and 10 c. For example, in FIG. 3A, the clean-cutsurfaces (e.g., m-plane) may be disposed up and down, and the tworemaining cut surfaces (e.g., a-plane) may be disposed left and right.The clean-cut surfaces may be arranged on the left and right of a viewerwho observes the display of FIG. 1 .

The first, second, and third light emitting devices 10 a, 10 b, and 10 cmay have the structure described above with reference to FIG. 2A andFIG. 2B, but the inventive concepts are not limited thereto, and variouslight emitting devices having a lateral or flip chip structure may beused.

The step adjustment layer 127 covers the first, second, and third lightemitting devices 10 a, 10 b, and 10 c. The step adjustment layer 127 hasopenings 127 a exposing the first and second electrode pads 31 and 33 ofthe light emitting devices 10 a, 10 b, and 10 c. The step adjustmentlayer 127 may facilitate formation of the connection layers 129 a, 129b, 129 c, and 129 d and the bumps 133 a, 133 b, 133 c, and 133 d. Inparticular, the step adjustment layer 127 may be formed to equalizeelevations of locations where the bumps 133 a, 133 b, 133 c, and 133 dare to be formed. The step adjustment layer 127 may be formed of, forexample, photosensitive polyimide.

The step adjustment layer 127 may have a concave-convex pattern along anedge thereof as shown in FIG. 3A. A shape of the concave-convex patternmay vary. A depth and a width of a concave portion formed to have theconcave-convex pattern or a depth and a width of a convex portiontherein may be adjusted. The concave-convex pattern formed on the stepadjustment layer 127 may reduce compressive stress applied to theadhesive layer 125 by the step adjustment layer 127, and thus, mayprevent peelings of the step adjustment layer 127 and the adhesive layer125.

The step adjustment layer 127 may be formed to partially expose an edgeof the adhesive layer 125 as illustrated in FIG. 3A, but the inventiveconcepts are not limited thereto. In particular, the step adjustmentlayer 127 may be disposed in a region surrounded by edges of theadhesive layer 125.

The connection layers 129 a, 129 b, 129 c, and 129 d are formed on thestep adjustment layer 127. The connection layers 129 a, 129 b, 129 c,and 129 d may be connected to the first and second electrode pads 31 and33 of the first, second, and third light emitting devices 10 a, 10 b,and 10 c through the openings 127 a of the step adjustment layer 127.

For example, the connection layer 129 a may be electrically connected toa first conductivity type semiconductor layer of the first lightemitting device 10 a, the connection layer 129 b may be electricallyconnected to a first conductivity of the second light emitting device 10b, the connection layer 129 c may be electrically connected to a firstconductivity type semiconductor layer of the third light emitting device10 c, and the connection layer 129 d may be commonly electricallyconnected to second conductivity type semiconductor layers of the first,second, and third light emitting devices 10 a, 10 b, and 10 c. Theconnection layers 129 a, 129 b, 129 c, and 129 d may be formed togetheron the step adjustment layer 127, and may include, for example, Au.

The bumps 133 a, 133 b, 133 c, and 133 d are formed on the connectionlayers 129 a, 129 b, 129 c, and 129 d, respectively. For example, thefirst bump 133 a may be electrically connected to the first conductivitytype semiconductor layer of the first light emitting device 10 a throughthe connection layer 129 a, the second bump 133 b may be electricallyconnected to the first conductivity type semiconductor layer of thesecond light emitting device 10 b through the connection layer 129 b,and the third bump 133 c may be electrically connected to the firstconductivity type semiconductor layer of the third light emitting device10 c through the connection layer 129 c. The fourth bump 133 d may becommonly electrically connected to the second conductivity typesemiconductor layers of the first, second, and third light emittingdevices 10 a, 10 b, and 10 c through the connection layer 129 d. Thebumps 133 a, 133 b, 133 c, and 133 d may be formed of, for example,metal and/or a metal alloy, such as AuSn, SnAg, Sn, CuSn, CuN, CuAg, Sb,Ni, Zn, Mo, Co, solder, or the like.

The protection layer 131 may cover side surfaces of the bumps 133 a, 133b, 133 c, and 133 d, and may cover the step adjustment layer 127. Inaddition, the protection layer 131 may cover the adhesive layer 125exposed around the step adjustment layer 127. The protection layer 131may be formed of, for example, a photosensitive solder resist (PSR),and, accordingly, the protection layer 131 may be patterned firstthrough photolithography and development processes, and then the bumps133 a, 133 b, 133 c, and 133 d may be formed. As such, the protectionlayer 131 may be formed to have openings exposing the contact layers 129a, 129 b, 129 c, and 129 d, and the bumps 133 a, 133 b, 133 c, and 133 dmay be formed in the openings of the protection layer 131. In someexemplary embodiments, the bumps 133 a, 133 b, 133 c, and 133 d may beomitted.

The protection layer 131 may be formed of a light absorbing material,such as a white reflective material or a black epoxy, to prevent lightleakage.

FIG. 4A is a schematic plan view illustrating a pixel module 1000according to an exemplary embodiment, FIG. 4B is a schematiccross-sectional view taken along line C-C of FIG. 4A, FIG. 4C is a rearview of the pixel module 1000, and FIG. 4D is a circuit diagram of thepixel module 1000.

Referring to FIGS. 4A and 4B, the pixel module 1000 includes a circuitboard 1001 and unit pixels 100 arranged on the circuit board 1001. Thepixel module 1000 may further include a cover layer 1010 covering theunit pixels 100.

The circuit board 1001 may have a circuit for electrically connecting apanel substrate 2100 (see FIG. 1 ) and light emitting devices 10 a, 10b, and 10 c. The circuit in the circuit board 1001 may be formed to havea multilayer structure. The circuit board 1001 may also include apassive circuit for driving the light emitting devices 10 a, 10 b, and10 c in a passive matrix driving manner, or an active circuit fordriving the light emitting devices 10 a, 10 b, and 10 c in an activematrix driving manner. The circuit board 1001 may include pads 1003exposed on a surface thereof. The pads 1003 may be arranged tocorrespond to the bumps in the unit pixels 100 to be mounted thereon.

Since the configuration of the unit pixels 100 is substantially the sameas that described with reference to FIGS. 3A and 3B, repeateddescriptions thereof will be omitted to avoid redundancy. The unitpixels 100 may be arranged on the circuit board 1001. The unit pixels100 may be arranged in a 2×2 matrix as shown in FIG. 4A, but theinventive concepts are not limited thereto. For example, in someexemplary embodiments, the unit pixels 100 may be arranged in variousmatrices, such as 2×3, 3×3, 4×4, 5×5, or the like.

The unit pixels 100 are bonded to the circuit board 1001 by a bondingmaterial 1005. For example, the bonding material 1005 may bond the bumps133 a, 133 b, 133 c, and 133 d to the pads 1003. When the bumps 133 a,133 b, 133 c, and 133 d are formed of solder, the bonding material 1005may be omitted.

The cover layer 1010 covers a plurality of unit pixels 100. The coverlayer 1010 may improve the contrast of the displaying apparatus bypreventing optical interference between the unit pixels 100.

The cover layer 1010 may be formed of, for example, a dry-film typesolder resist (DFSR), a photoimageable solder resist (PSR), a blackmaterial (BM), an epoxy molding compound (EMC), or the like. The coverlayer 1010 may be formed using a technique, such as lamination, spincoating, slit coating, printing, or the like, without being limitedthereto.

A displaying apparatus 10000 may be provided by mounting the pixelmodules 1000 on the panel substrate 2100 of FIG. 1 as shown in FIG. 4Aand FIG. 4B. The circuit board 1001 has bottom pads connected to thepads 1003. The bottom pads may be arranged in a one-to-onecorrespondence with the pads 1003, but the number of the bottom pads maybe reduced through a common connection. The pixel module 1000 having theunit pixels 100 arranged in a 2×2 matrix will be described withreference to FIG. 4C and FIG. 4D according to an exemplary embodiment.

FIG. 4C illustrates a rear view of the pixel module 1000, and bottompads C1, C2, R1, R2, G1, G2, B1, and B2 of the circuit board 1001 areillustrated. Since the pixel modules 1000 are arranged in a 2×2 matrix,a total of four pixel modules are arranged on the circuit board 1001.Three light emitting devices 10 a, 10 b, and 10 c and four bumps 133 a,133 b, 133 c, and 133 d are disposed on each pixel module 1000.Accordingly, sixteen pads 1003 corresponding to the bumps of the fourunit pixels 100 may be provided on the circuit board 1001. However,according to an exemplary embodiment, only eight bottom pads may bedisposed, and the eight bottom pads may be connected to the panelsubstrate 2100 to individually drive each of the light emitting devices10 a, 10 b, and 10 c.

FIG. 4D illustrates a schematic circuit diagram in which each of thelight emitting devices 10 a, 10 b, and 10 c are connected to the bottompads C1, C2, R1, R2, G2, G2, B1, and B2.

Referring to FIG. 4D, the bottom pad C1 is commonly connected tocathodes of the light emitting devices 10 a, 10 b, and 10 c disposed inthe left column, and the bottom pad C2 is commonly connected to cathodesof the light emitting devices 10 a, 10 b, and 10 c disposed in the rightcolumn.

In the unit pixels 100 arranged in the upper row, the bottom pad B1 maybe connected to anodes of the first light emitting devices 10 a, thebottom pad G1 may be connected to anodes of the second light emittingdevices 10 b, and the bottom pad R1 may be connected to anodes of thethird light emitting devices 10 c.

In the unit pixels 100 arranged in the lower row, the bottom pad B2 maybe connected to the anodes of the first light emitting devices 10 a, thebottom pad G2 may be connected to the anodes of the second lightemitting devices 10 b, and the bottom pad R2 may be connected to theanodes of the third light emitting devices 10 c.

As used herein, the bottom pads R1, G1, B1, R2, G2, and B2 representpads connected to red, green, and blue light emitting devices,respectively. However, the order of arrangement of the red, green, andblue light emitting devices may be changed, and, accordingly, locationsto which the bottom pads R1, G1, B1, R2, G2, and B2 are connected mayalso be changed. For example, the circuit diagram of FIG. 4D shows thebottom pads when the first light emitting devices 10 a are blue lightemitting devices, the second light emitting devices 10 b are green lightemitting devices, and the third light emitting devices 10 c are redlight emitting devices. Alternatively, the first light emitting devices10 a may be the blue light emitting devices, and the third lightemitting devices 10 c may be the red light emitting devices, and, inthis case, the locations of the bottom pads R1 and R2 and the bottompads B1 and B2 may be interchanged.

According to the illustrated exemplary embodiment, since the bottom padsC1 and C2 are commonly connected to the cathodes of the light emittingdevices in each column, and each of the bottom pads R1, G1, B1, R2, B2,and G2 are connected to the anodes of the two light emitting devices,and thus, each of the light emitting devices 10 a, 10 b, and 10 c may bedriven independently while reducing the total number of the bottom pads.

Although it is described and illustrated that the bottom pads C1 and C2are connected to the cathodes of the light emitting devices, and thebottom pads R1, G1, B1, R2, B2 and G2 are connected to the anodes of thelight emitting device in the illustrated exemplary embodiment, theinventive concepts are not limited thereto. For example, in someexemplary embodiments, the bottom pads C1 and C2 may be connected to theanodes of the light emitting devices, and the bottom pads R1, G1, B1,R2, B2 and G2 may be connected to the cathodes of the light emittingdevice, as shown in FIG. 4E.

Although the electrical connection of the pixel module 1000 has beendescribed with reference to the unit pixels 100 arranged in a 2×2matrix, the number of the bottom pads may be reduced using a commonconnection circuit even when the unit pixels 100 are arranged in anothermatrix, such as 3×3, 5×5, or the like.

The light emitting devices 10 a, 10 b, and 10 c in the pixel module 1000may be individually driven by a driving IC disposed on the panelsubstrate 2100, and images may be implemented by a plurality of pixelmodules 1000.

FIG. 5A, FIG. 5B, and FIG. 5C are schematic plan views illustrating aunit pixel according to exemplary embodiments. In particular, FIG. 5A,FIG. 5B, and FIG. 5C illustrate various modified examples of aconcave-convex pattern of a step adjustment layer 127.

The step adjustment layer 127 a may have a relatively widerconcave-convex pattern than those described above as shown in FIG. 5A.In particular, relatively narrow and slender portions may be disposed atcorners of the step adjustment layer 127 a, thereby preventingconcentration of stress at the corners of the step adjustment layer 127a.

More particularly, a concave portion and a convex portion of a stepadjustment layer 127 a may have an arc shape having a constant radius,and radiuses of the concave portion and the convex portion may besubstantially the same or be different from each other.

A bottom of a concave portion of a step adjustment layer 127 b may besubstantially flat as shown in FIG. 5B. A concave-convex pattern of astep adjustment layer 127 c may have a serrated shape as shown in FIG.5C.

The concave-convex pattern of the step adjustment layer 127 may bevariously modified, and, in particular, the step adjustment layer 127may be formed to prevent stress from concentrating on the corners whilethe step adjustment layer 127 contracts.

The light emitting device 10 described with reference to FIG. 2A andFIG. 2B has the connection tip 55 b on a side surface, which is oppositeto the surface of the light emitting structure on which the first andsecond electrode pads 31 and 33 are disposed. In some exemplaryembodiments, a connection tip 55 b may be disposed on the same sidesurface of the surface on which the first and second electrode pads 31and 33 are disposed. A location at which the connection tip 55 b isformed is related to a method of transferring the light emitting devices10, which will be described in more detail later.

FIGS. 6A through 6K are schematic cross-sectional views illustrating amethod of transferring light emitting devices according to an exemplaryembodiment.

Referring to FIG. 6A, light emitting devices 10 are formed on asubstrate 51. The substrate 51 may be a substrate capable of growingsemiconductor layers of the light emitting devices 10 thereon. Thesubstrate 51 may be, for example, a sapphire substrate or a GaNsubstrate for growing an AlInGaN-based semiconductor layer, or a GaAssubstrate for growing AlNGaP-based semiconductor layers. For example,when the light emitting device 10 is a blue light emitting device or agreen light emitting device, the sapphire substrate or the GaN substratemay be used, and, when the light emitting device 10 is a red lightemitting device, the GaAs substrate may be used.

Referring to FIG. 6B, a first mask layer 53 is formed on the substrate51 to cover the light emitting devices 10. The first mask layer 53 maybe formed to completely cover the light emitting devices 10, and mayformed over the light emitting devices 10 to have a predeterminedthickness.

Referring to FIG. 6C, a plurality of holes Hs are formed in the firstmask layer 53. Each of the plurality of holes Hs may be formed over theplurality of light emitting devices 10, and at least one hole H may beformed on each of the light emitting devices 10. In the illustratedexemplary embodiment, three holes Hs are formed on each light emittingdevice 10, and the three holes Hs are arranged asymmetrically to atleast one direction where the light emitting devices 10 are arranged.Here, the three holes Hs in the drawing are arranged asymmetrically to adirection, which is perpendicular to the direction where the lightemitting devices 10 are arranged.

The first mask layer 53 may be formed of a photosensitive material, andthe plurality of holes Hs may be formed through a photolithographyprocess. The plurality of holes Hs may be formed through an exposure anddevelopment processes, or through an etching process. The plurality ofholes Hs may be formed to have substantially a triangular shape as shownin the drawing. However, the number of holes Hs formed in each lightemitting device is not limited to three.

Referring to FIG. 6D, a connection layer 55 is formed on the first masklayer 53. The connection layer 55 is formed on the first mask layer 53while filling the plurality of holes Hs formed in the first mask layer53. Since at least one hole H is formed over each light emitting device10, the connection layer 55 may be connected to the light emittingdevice 10 through at least one hole H formed over the light emittingdevice 10. A connection portion 55 a connected to the light emittingdevice 10 by filling the hole H may be formed together while theconnection layer 55 is formed.

The connection layer 55 may be formed of an organic material, such aspoly dimethylpolysiloxane (PDMS), epoxy, acryl, color polyimide, or thelike, but it is not limited thereto. The connection layer 55 may have alight transmittance of 90% or more, and a refractive index of about 1.4to about 1.7.

Referring to FIG. 6E, a first temporary substrate 57 is coupled to anupper surface of the connection layer 55. The first temporary substrate57 may be a polymer substrate, such as PET, PEN, PI sheet, or the like,or may be a substrate, such as glass, PC, PMMA, or the like. When thefirst temporary substrate 57 is coupled to the upper surface of theconnection layer 55, bubbles generated in the connection layer 55 in avacuum state may be removed, and a hardening process of the connectionlayer 55 may be performed at a temperature lower than a melting point ofthe first mask layer 53. In this manner, the first temporary substrate57 may be coupled to the connection layer 55.

When the first temporary substrate 57 is coupled to the connection layer55, the substrate 51 is removed from the light emitting devices 10 asshown in FIG. 6F. The substrate 51 may be removed by a laser lift-offprocess or a wet etching process. For example, if the substrate 51 is asapphire substrate, the substrate 51 may be removed by the laserlift-off process or a chemical lift-off process, and if the substrate 51is a GaAs substrate, the GaAs substrate may be removed by the wetetching process.

Referring to FIG. 6G, in a state where the substrate 51 is removed, thefirst mask layer 53 is removed from the light emitting devices 10. Thefirst mask layer 53 may be removed using, for example, acetone, adedicated striper, etching, or the like. As the first mask layer 53 isremoved, each of the light emitting devices 10 is connected to theconnection layer 55 through the at least one connection portion 55 a andmaintained as shown in the drawing.

Referring to FIG. 6H, after the first mask layer 53 is removed from thelight emitting devices 10, a second temporary substrate 59 is coupled tolower surfaces of the light emitting devices 10. The second temporarysubstrate 59 may be a rubber or UV sheet, or may be a polymer substrate,such as PET, PEN, PI sheet, or the like, or a substrate, such as glass,PC, PMMA, or the like.

When coupling the second temporary substrate 59 to the light emittingdevices 10 is completed, the light emitting devices 10 are removed fromthe connection layer 55 using the second temporary substrate 59 as shownin FIG. 6I. By applying an external force to the second temporarysubstrate 59 coupled to the light emitting devices 10 in a directionaway from the first temporary substrate 57, e.g., downward, the at leastone connection portion 55 a connected to the light emitting devices 10may be cut, and the light emitting devices 10 are separated from theconnection layer 55.

The external force applied to the second temporary substrate 59 as shownin the drawing may be applied in a direction perpendicular to theconnection layer 55 at one side of the second temporary substrate 59. Assuch, each of the light emitting devices 10 may be separated from theconnection layer 55 such that the at least one connection portion 55 aconnected to each light emitting device 10 is sequentially cut from oneside of the second temporary substrate 59.

Referring to FIG. 6J, the light emitting devices 10 separated from theconnection layer 55 are disposed on the second temporary substrate 59with a predetermined interval. In this case, at least one connection tip55 b may be formed on each of the light emitting devices 10 as a residuewhile the connection portion 55 a is cut. Accordingly, the connectiontip 55 b is formed of the same material as the connection layer 55.Since the connection portion 55 a is cut by an external force, thethicknesses of the connection tips 55 b may be irregular and bedifferent from one another.

Referring to FIG. 6J and FIG. 6K, a portion of the light emittingdevices 10 disposed on the second temporary substrate 59 is transferredto another substrate using a pickup 70. The pickup 70 may include anelastomeric stamp, for example.

The pickup 70 picks up and transfers a portion of the plurality of lightemitting devices 10. More particularly, the pickup 70 selectively picksup the light emitting devices 10 in accordance with an interval betweenlight emitting devices 10, which will be arranged on the transparentsubstrate 121. As such, as shown in the drawing, the pickup 70 picks uponly some of the light emitting devices 10 having a certain interval ata time. The interval between the light emitting devices 10 picked up mayvary depending on an interval between pixels in the transparentsubstrate 121 onto which the light emitting devices 10 are to betransferred.

After the light emitting devices 10 are arranged on the transparentsubstrate 121 to correspond to a plurality of unit pixels 100, thetransparent substrate 121 may be cut in each pixel unit to form the unitpixel 100. As such, the light emitting devices 10 are transferred ontothe transparent substrate 121 to correspond to each unit pixel 100.

The pickup 70 picks up the light emitting devices 10 that are spacedapart at an interval that matches an interval between the unit pixels100, and one of the first light emitting device 10 a, the second lightemitting device 10 b, and the third light emitting device 10 c may bepicked up to be arranged in a single unit pixel 100.

According to an exemplary embodiment, the light emitting devices 10 maybe picked up in a state where the first and second electrode pads 31 and33 are disposed thereon, and may be also transferred to the transparentsubstrate 121 in this state. As such, light generated in the lightemitting structure may be emitted to the outside through the transparentsubstrate 121. In another exemplary embodiment, the light emittingdevices 10 may be mounted on a circuit board, and, in this case, thefirst and second electrode pads 31 and 33 may be mounted toward thecircuit board. In this case, an additional temporary substrate may beused in the process of mounting the light emitting devices 10 on thecircuit board using the pickup 70. More particularly, the light emittingdevices 10 picked up through the pickup 70 may be first arranged on theadditional temporary substrate at the interval between the unit pixels100. Thereafter, the light emitting devices 10 disposed on theadditional temporary substrate may be transferred to the circuit boardat a time. As such, the light emitting devices 10 may be transferred, sothat the first and second electrode pads 31 and 33 may be bonded to thecircuit board.

FIGS. 7A through 7L are schematic cross-sectional views illustrating amethod of transferring light emitting devices according to anotherexemplary embodiment.

Referring to FIG. 7A, light emitting devices 10 are grown on a substrate51. The substrate 51 may be a substrate capable of growing semiconductorlayers of the light emitting device 10 thereon. When the light emittingdevice 10 is a blue light emitting device or a green light emittingdevice, a sapphire substrate or a GaN substrate may be used, and, whenthe light emitting device 10 is a red light emitting device, a GaAssubstrate may be used.

Referring to FIG. 7B, a first mask layer 53 is formed on the substrate51 to cover the light emitting devices 10. The first mask layer 53 maybe formed to cover each of the light emitting devices 10, and may beformed to have a predetermined thickness on an upper surfaces of thelight emitting devices 10.

Subsequently, referring to FIG. 7C, a plurality of holes Hs are formedin the first mask layer 53. At least one hole H may be formed on each ofthe light emitting devices 10. According to the illustrated exemplaryembodiment, three holes Hs may be formed on each light emitting device10, and the three holes Hs are arranged asymmetrically to at least onedirection where the light emitting devices 10 are arranged. The threeholes Hs in the drawing are arranged asymmetrically to a direction,which is perpendicular to the direction where the light emitting devices10 are arranged.

The first mask layer 53 may be formed of a photosensitive material, andthe plurality of holes Hs may be formed through a photolithographyprocess. For example, the holes Hs may be formed through an exposure anddevelopment processes or an etching process may be used. The pluralityof holes Hs may be formed in substantially a triangular shape as shownin the drawing.

Referring to FIG. 7D, a connection layer 55 is formed on the first masklayer 53. The connection layer 55 is formed on the first mask layer 53while filling the plurality of holes Hs formed in the first mask layer53. Since each of the plurality of holes Hs is formed over the lightemitting device 10, the connection layer 55 may be connected to thelight emitting devices through at least one hole H formed over the lightemitting device 10. A portion of the connection layer 55 may form aconnection portion 55 a by filling the at least one hole H formed overthe light emitting device 10.

The connection layer 55 may be formed of an organic material, such aspoly dimethylpolysiloxane (PDMS), epoxy, acryl, color polyimide, or thelike, but it is not limited thereto. The connection layer 55 may have alight transmittance of 90% or more, and a refractive index of about 1.4to about 1.7.

Referring to FIG. 7E, a first temporary substrate 57 is coupled to anupper surface of the connection layer 55. The first temporary substrate57 may be a polymer substrate, such as PET, PEN, PI sheet, or the like,or may be a substrate, such as glass, PC, PMMA, or the like. A filmlayer 61 and a buffer layer 63 may be disposed between the firsttemporary substrate 57 and the connection layer 55, respectively. Forexample, the film layer 61 may be disposed over the connection layer 55,the buffer layer 63 may be disposed over the film layer 61, and thefirst temporary substrate 57 may be disposed over the buffer layer 63.The buffer layer 63 may be formed of a material that may be melt by heator UV irradiation.

When the first temporary substrate 57 is coupled to the upper surface ofthe connection layer 55, bubbles generated in the connection layer 55 ina vacuum state may be removed, and a hardening process of the connectionlayer 55 may be performed at a temperature lower than a melting point ofthe first mask layer 53. In this manner, the first temporary substrate57 may be coupled to the connection layer 55.

Referring to FIG. 7F, the substrate 51 is removed from the lightemitting devices 10. The substrate 51 may be removed by a laser lift-offprocess or a wet etching process. For example, when the substrate 51 isa sapphire substrate, it may be removed by the laser lift-off process ora chemical lift-off process, and when the substrate 51 is a GaAssubstrate, it may be removed by the wet etching process.

Referring to FIG. 7G, the first mask layer 53 is removed from the lightemitting devices 10 in a state that the substrate 51 is removed. Thefirst mask layer 53 may be removed using, for example, acetone, adedicated striper, dry etching, or the like. As such, the light emittingdevices 10 are connected to the connection layer 55 through at least oneconnection portion 55 a connected to each light emitting device 10 andmaintained as shown in the drawing.

Referring to FIG. 7H, the first temporary substrate 57 coupled to theupper surface of the connection layer 55 is removed. The first temporarysubstrate 57 may be removed by heat or UV irradiation. In this manner,the first temporary substrate 57 may be removed without damaging thefilm layer 61 because the buffer layer 63 is formed of a material thatmay be melt by heat or UV irradiation.

Referring to FIG. 7I, a second temporary substrate 59 is coupled to alower surface of the light emitting devices 10. The second temporarysubstrate 59 may be a rubber or UV sheet, or may be a polymer substrate,such as PET, PEN, PI sheet, or the like, or a substrate, such as glass,PC, PMMA, or the like.

When the second temporary substrate 59 is coupled to the light emittingdevices 10, the light emitting devices 10 are removed from theconnection layer 55 using the second temporary substrate 59 as shown inFIG. 7J. By applying an external force downward to the second temporarysubstrate 59 coupled to the light emitting devices 10, the at least oneconnection portion 55 a connected to the light emitting devices 10 iscut, and the light emitting devices 10 are separated from the connectionlayer 55.

The external force applied to the second temporary substrate 59 may beapplied in a direction perpendicular to the connection layer 55 at oneside of the second temporary substrate 59. As such, each of the lightemitting devices 10 may be separated from the connection layer 55, suchthat the connection portions 55 a connected to each light emittingdevice 10 are sequentially cut.

Referring to FIG. 7K, the light emitting devices 10 separated from theconnection layer 55 are disposed on the second temporary substrate 59 ata predetermined interval. At least one connection tip 55 b may be formedon each of the light emitting devices 10 as a residue while theconnection portion 55 a is cut. As such, the connection tip 55 b isformed of the same material as the connection layer 55. Since theconnection tip 55 b is formed while the connection portion 55 a is cutby an external force, the thicknesses of the connection tips 55 b may bedifferent from one another. Also, the thicknesses of the connection tips55 b may be less than those of the first and second electrode pads 31and 33 as shown in the drawing.

Referring to FIGS. 7K and 7L, some of the light emitting devices 10disposed on the second temporary substrate 59 are transferred to anothersubstrate using a pickup 70. A substrate to be transferred may be atransparent substrate 121, but is not limited thereto. After the lightemitting devices 10 are transferred to the transparent substrate 121 ina unit of unit pixels 100, the transparent substrate 121 may be cut inthe unit of the unit pixels 100 in some exemplary embodiments.

FIGS. 8A through 8K are schematic cross-sectional views illustrating amethod of transferring light emitting devices according to anotherexemplary embodiment.

Referring to FIG. 8A, light emitting devices 10 are formed on asubstrate 51. The substrate 51 is a substrate capable of growingsemiconductor layers of the light emitting device 10 thereon, such as asapphire substrate, a GaN substrate, or a GaAs substrate. For example,the substrate 51 may be the sapphire substrate when the light emittingdevice 10 is a blue light emitting device or a green light emittingdevice, and may be a GaAs substrate when the light emitting device 10 isa red light emitting device.

Referring to FIG. 8B, a first mask layer 53 is formed on the substrate51 to cover the light emitting devices 10. The first mask layer 53 maybe formed to cover each of the light emitting devices 10, and may beformed to have a predetermined thickness on an upper surfaces of thelight emitting devices 10. The first mask layer 53 may be formed of, forexample, a photosensitive material.

Referring to FIG. 8C, a first temporary substrate 57 is coupled onto thefirst mask layer 53. The first temporary substrate 57 may be a polymersubstrate, such as PET, PEN, PI sheet, or the like, or may be asubstrate, such as glass, PC, PMMA, or the like. A buffer layer 63 maybe disposed between the first temporary substrate 57 and the first masklayer 53. The buffer layer 63 may be disposed on the first mask layer53, and the first temporary substrate 57 may be disposed on the bufferlayer 63.

Referring to FIG. 8D, the substrate 51 is removed from the lightemitting devices 10. The substrate 51 may be removed using a laserlift-off process, a wet etching process, or the like. When the substrate51 is a sapphire substrate, the substrate 51 may be removed by the laserlift-off process or a chemical lift-off process. When the substrate 51is a GaAs substrate, the substrate 51 may be removed by the wet etchingprocess.

Referring to FIG. 8E, a lower surface of the light emitting devices 10and a lower surface of the first mask layer 53 may be exposed as thesubstrate 51 is removed. A second mask layer 65 is formed under thelight emitting devices 10 and the first mask layer 53. The second masklayer 65 may cover the lower surface of the light emitting devices 10,and may have a thickness less than that of the first mask layer 53.

Referring to FIG. 8F, a plurality of holes Hs are formed in the secondmask layer 65. At least one hole H may be formed under each lightemitting device 10. According to the illustrated exemplary embodiment,three holes Hs may be formed under each light emitting device 10, andthe three holes Hs are arranged asymmetrically to at least one directionwhere the light emitting devices 10 are arranged. The three holes Hs inthe drawing are arranged asymmetrically to a direction which isperpendicular to the direction where the light emitting devices 10 arearranged.

The second mask layer 65 may be formed with a photosensitive material asthe first mask layer 53, and the plurality of holes Hs may be formed bya photolithography process, for example. The plurality of holes Hs maybe formed to have substantially a triangular shape as shown in thedrawing.

Referring to FIG. 8G, a connection layer 55 is formed under the secondmask layer 65. The connection layer 55 is formed under the second masklayer 65 while filling the plurality of holes Hs formed in the secondmask layer 65. Since each of the plurality of holes Hs is formed underthe light emitting device 10, the connection layer 55 may be connectedto the light emitting devices 10 through the holes Hs formed under thelight emitting devices 10. Connection portions 55 a filling the holes Hsare formed together with the connection layer 55. The connectionportions 55 a may directly contact the first conductivity typesemiconductor layer 23 of the light emitting device 10.

The connection layer 55 may include an organic material, such as polydimethylpolysiloxane (PDMS), epoxy, acryl, color polyimide, or the like,but it is not limited thereto. The connection layer 55 may have a lighttransmittance of 90% or more, and a refractive index of about 1.4 toabout 1.7.

A second temporary substrate 59 is coupled to a lower surface of theconnection layer 55. The second temporary substrate 59 may be a polymersubstrate as the first temporary substrate 57, such as PET, PEN, PIsheet, or the like, or may be a substrate such as glass, PC, PMMA, orthe like.

Referring to FIG. 8H, the first temporary substrate 57 coupled to anupper surface of the connection layer 55 is removed. The first temporarysubstrate 57 may be removed by heat or UV irradiation. The firsttemporary substrate 57 may be removed from the first mask layer 53 asthe buffer layer 63 is formed of a material that may be melt by heat orUV irradiation.

Referring to FIG. 8I, the first mask layer 53 and the second mask layer65 are removed from the light emitting devices 10. The first mask layer53 and the second mask layer 65 may be removed using, for example,acetone, a dedicated striper, dry etching, or the like. As shown in thedrawing, the light emitting devices 10 are connected to the connectionlayer 55 by at least one connection portion 55 a connected to each lightemitting device 10 and maintained.

Once the first and second mask layers 53 and 65 are removed, the lightemitting devices 10 are disposed over the second temporary substrate 59while being connected to the connection layer 55 and the connectionportion 55 a as shown in FIG. 8J. A portion of the light emittingdevices 10 disposed over the second temporary substrate 59 may betransferred to another substrate using a pickup 70.

Referring to FIG. 8K, each of the light emitting devices 10 picked up bythe pickup 70 is separated from the connection layer 55 as theconnection portion 55 a is snapped from the connection layer 55. Thepickup 70 picks up the light emitting devices 10 over the light emittingdevices 10, and a residue of the connection portion 55 a is disposedunder the light emitting device 10. As such, at least one connection tip55 b may be formed under each of the light emitting devices 10.

Thereafter, the light emitting devices 10 picked up by the pickup 70 maybe transferred to the transparent substrate 121, and the transparentsubstrate 121 may be cut in a unit of individual unit pixel 100 toprovide the unit pixels 100.

The light emitting devices 10 are transferred to the transparentsubstrate 121 by the method of transferring the light emitting devicedescribed above. An adhesive layer 125 may be formed on the transparentsubstrate 121 in advance, and the light emitting devices 10 may beattached onto the transparent substrate 121 by the adhesive layer 125.Thereafter, a step adjustment layer 127 and connection layers 129 a, 129b, 129 c, and 129 d, a protection layer 131, and bumps 133 a, 133 b, 133c, and 133 d are formed, and then the transparent substrate 121 is cutoff to manufacture the unit pixel 100 described with reference to FIG.3A and FIG. 3B. A pixel module 1000 may be manufactured by arranging theunit pixels 100 on a circuit board 1001, and a displaying apparatus10000 may be provided by arranging the pixel modules 1000 on a panelsubstrate 2100.

FIGS. 9A through 9O are schematic plan views illustrating a lightemitting device according to exemplary embodiments.

In light emitting devices 10 shown in FIGS. 9A through 9O according toexemplary embodiments, a connection tip 55 b is disposed on an oppositeside to first and second electrode pads 31 and 33. Hereinafter, alocation of the connection tip 55 b will exemplarily be described withreference to a location relative to those of the first and secondelectrode pads 31 and 33. However, the connection tip 55 b and the firstand second electrode pads 31 and 33 are disposed on sides of the lightemitting device 10 which are opposite to each other, and they do notcontact each other.

Referring to FIG. 9A, in a first modified example, three connection tips55 b are formed in the light emitting device 10, which are disposedbetween the first and second electrode pads 31 and 33. Moreparticularly, the three connection tips 55 b are formed on an uppersurface of the light emitting device 10. The first and second electrodepads 31 and 33 are formed under the light emitting device 10. A shape ofthe three connection tips 55 b may be formed in substantially atriangular shape. A total area of the three connection tips 55 b may be,for example, about 1.26% as compared with a planar area of the lightemitting device 10.

Referring to FIG. 9B, in a second modified example, three connectiontips 55 b are formed in the light emitting device 10, which are disposedoutside of the first and second electrode pads 31 and 33. Two connectiontips 55 b are disposed near the first electrode pad 31 adjacent to outercorners of the first electrode pad 31, respectively. The remainingconnection tip 55 b is disposed outside the second electrode pad 33. Inthis case, the two connection tips 55 b disposed on sides of the firstelectrode pad 31 may be disposed in a direction different from adirection where the first and second electrode pads 31 and 33 aredisposed.

A total area of the three connection tips 55 b may be, for example,about 0.65% as compared with the planar area of the light emittingdevice 10.

Referring to FIG. 9C, in a third modified example, four connection tips55 b are formed on the light emitting device 10, which are widelydisposed on the plane of the light emitting device 10. Moreparticularly, two of the four connection tips 55 b are disposed at alocation overlapping with the first and second electrode pads 31 and 33,and the other two are disposed between the first and second electrodepads 31 and 33. In this case, each of the two connection tips 55 bdisposed at a location overlapping with the first and second electrodepads 31 and 33 may be disposed at centers of the first and secondelectrode pads 31 and 33.

The connection tips 55 b of FIG. 9C may be formed to have substantiallya diamond shape, and the four connection tips 55 b may be disposed ateach corner of the diamond shape. In this case, a total area of the fourconnection tips 55 b may be, for example, about 1.22% as compared withthe planar area of the light emitting device 10.

Referring to FIG. 9D, in a fourth modified example, four connection tips55 b are formed in the light emitting device 10. Two of the fourconnection tips 55 b are disposed to partially overlap with the firstand second electrode pads 31 and 33, and the other two are disposedbetween the first and second electrode pads 31 and 33. The connectiontips 55 b of the fourth modified example may be disposed at a relativelysmall interval as compared with the connection tips 55 b of the thirdmodified example.

Each of the connection tips 55 b may be formed to have substantially adiamond shape, and the four connection tips 55 b may be disposed at eachcorner of the diamond shape. In this case, a total area of the fourconnection tips 55 b may be, for example, about 1.22% as compared withthe planar area of the light emitting device 10.

Referring to FIG. 9E, in a fifth modified example, four connection tips55 b are formed in the light emitting device 10. The connection tips 55b of the fifth modified example may be disposed in the same manner asthe connection tips 55 b of the third modified example. In this case, atotal area of the connection tips 55 b of the fifth modified example maybe greater than that of the connection tips 55 b of the third modifiedexample, and may be, for example, about 2.71% as compared with theplanar area of the light emitting device 10.

Referring to FIG. 9F, in a sixth modified example, four connection tips55 b are formed in the light emitting device 10. The connection tips 55b of the sixth modified example may be disposed in the same manner asthe connection tips 55 b of the fourth modified example. In this case, atotal area of the connection tips 55 b of the sixth modified example maybe greater than that of the connection tips 55 b of the fourth modifiedexample, and may be, for example, about 2.71% as compared with theplanar area of the light emitting device 10.

Referring to FIG. 9G, in a seventh modified example, three connectiontips 55 b are formed in the light emitting device 10, which are disposedat locations overlapping with the first and second electrode pads 31 and33. More particularly, two connection tips 55 b are disposed atlocations overlapping with the first electrode pads 112, and theremaining connection tip 55 b is disposed at a location overlapping withthe second electrode pad 33. The two connection tips 55 b overlappingthe first electrode pad 31 may be disposed in a direction different froma direction in which the first and second electrode pads are disposed.

A total area of the three connection tips 55 b may be, for example,about 0.58% as compared with the planar area of the light emittingdevice 10.

Referring to FIG. 9H, in an eighth modified example, three connectiontips 55 b are formed in the light emitting device 10, which are disposedat locations partially overlapping with the first and second electrodepads 31 and 33. One of the three connection tips 55 b is disposed at alocation partially overlapping with the first electrode pad 31, and theother two connection tips 55 b are disposed at a location partiallyoverlapping with the second electrode pad 33. In this case, the threeconnection tips 55 b may be formed to have substantially a triangularshape, and the three connection tips 55 b may be disposed at each cornerof the triangular shape. The connection tips 55 b of the eighth modifiedexample are formed larger than the connection tips 55 b of the firstmodified example, and may be, for example, about 2.76% as compared withthe planar area of the light emitting device 10.

Referring to FIG. 9I, in a ninth modified example, four connection tips55 b are formed in the light emitting device 10, which are disposed atlocations overlapping with the first and second electrode pads 31 and33. Two of the four connection tips 55 b are disposed at locationsoverlapping with the first electrode pad 31, and the other two aredisposed at locations overlapping with the second electrode pad 33. Theconnection tips 55 b of the ninth modified example may be formed to havesubstantially a triangular shape. A total area of the connection tips 55b may be, for example, about 1.68% as compared with the planar area ofthe light emitting device 10.

Referring to FIG. 9J, in a tenth modified example, three connection tips55 b are formed in the light emitting device 10, which are disposed atlocations overlapping with the first and second electrode pads 31 and33. One of the three connection tips 55 b is disposed at a locationoverlapping with the first electrode pad 31, and the other two aredisposed at a location overlapping with the second electrode pad 33. Atotal area of the connection tips 55 b may be, for example, about 1.26%as compared with the planar area of the light emitting device 10.

Referring to FIG. 9K, in an eleventh modified example, three connectiontips 55 b are formed in the light emitting device 10. The connectiontips 55 b are disposed at locations overlapping with the first andsecond electrode pads 31 and 33. Two of the three connection tips 55 bare disposed at locations overlapping with the first electrode pad 31,and the remaining one is disposed at a location overlapping with thesecond electrode pad 33. A total area of the connection tips 55 b maybe, for example, about 1.26% as compared with the planar area of thelight emitting device 10.

Referring to FIG. 9L, in a twelfth modified example, a connection tip 55b formed in the light emitting device 10 is disposed between the firstand second electrode pads 31 and 33. The connection tip 55 b includes abase 55 ba having a longitudinal length perpendicular to a direction inwhich the first and second electrode pads 31 and 33 are disposed, afirst extension 55 bb disposed at one longitudinal end of the base 55 baand extending toward the first electrode pad 31, and a second extension55 bc disposed at the remaining longitudinal end of the base 55 ba andextending toward the second electrode pad 33. Each of the first andsecond extensions 55 bb and 55 bc may be formed to have a shape having anarrower width as a distance from the base 55 ba increases.

A total area of the connection tip 55 b may be, for example, about 1.92%as compared with the planar area of the light emitting device 10.

Referring to FIG. 9M, in a thirteenth modified example, a connection tip55 b formed in the light emitting device 10 is disposed between thefirst and second electrode pads 31 and 33. The connection tip 55 bincludes a base 55 ba having a longitudinal length perpendicular to adirection in which the first and second electrode pads are disposed, afirst extension 55 bb extending toward the first electrode pad 31 from acenter of the base 55 ba, and a second extension 55 bc extending towardthe second electrode pad 33 from a center of the base 55 ba. Each of thefirst and second extensions 55 bb and 55 bc may be formed in a shapehaving a narrower width as a distance from the base 55 ba increases.

A total area of the connection tip 55 b may be, for example, about1.161% as compared with the planar area of the light emitting device 10.

Referring to FIG. 9N, in a fourteenth modified example, four connectiontips 55 b are formed in the light emitting device 10. Two of the fourconnection tips 55 b are disposed at locations overlapping with thefirst and second electrode pads 31 and 33, and the other two aredisposed between the first and second electrode pads 31 and 33. Theconnection tips 55 b disposed on the first and second electrode pads 31and 33 may be disposed at an edge of the first and second electrode pads31 and 33, respectively. The connection tip 55 b overlapped with thefirst electrode pad 31 may be disposed at a location close to the secondelectrode pad 33 from the first electrode pad 31, and the connection tip55 b overlapped with the second electrode pad 33 may be disposed at alocation close to the first electrode pad 31 from the second electrodepad 33. A total area of the four connection tips 55 b may be, forexample, about 0.49% as compared with the planar area of the lightemitting device 10.

Referring to FIG. 9O, in a fifteenth modification, four connection tips55 b are formed in the light emitting device 10. One connection tip ofthe four connection tips 55 b is disposed at approximately a center ofthe light emitting device 10, two connection tips 55 b are disposed atlocations overlapping with the second electrode pad 33, and theremaining one connection tip 55 b is disposed at a location overlappingwith the first electrode pad 31. Three connection tips 55 b may bedisposed in a triangular shape near outline of the light emittingdevice, and the connection tip 55 b disposed at the center of the lightemitting device 10 may be located in the triangle formed by the threeconnection tips 55 b.

The two connection tips 55 b disposed at the locations overlapping withthe second electrode pad 33 may be disposed near edges of the secondelectrode pad 33, respectively, and may be disposed to face each otherwith respect to an elongated straight line passing through the center.

The connection tip 55 b disposed at the location overlapping with thefirst electrode pad 31 may be disposed near one edge of the firstelectrode pad 31, and may be disposed away from the elongated straightline passing through the center.

Each of the connection tips 55 b may have substantially a righttriangular shape, and the connection tip 55 b disposed at the center ofthe light emitting device 10 may be disposed in a direction which isopposite to a direction in which the other connection tips 55 b aredisposed as shown in the drawing.

When the light emitting devices 10 are separated from the connectionportion 55 using the connection tips 55 b, the connection tip 55 boverlapped with the first electrode pad 31 may be first formed, theconnection tip 55 b near the center may be formed next, and theconnection tips 55 b overlapped with the second electrode pad 33 may beformed last. As such, the light emitting devices 10 may be easilyseparated from the connection portion 55, and cracks which may otherwiseoccur in the light emitting devices 10 may be prevented.

When picking up or mounting the light emitting device 10, the lightemitting device 10 may be unstably picked up or mounted depending on thelocation of the connection tips, and thus, cracks may occur. Accordingto an exemplary embodiment, since the connection tips 55 b are disposedon both edges of the light emitting device 10 and near the center of thelight emitting device 10, respectively, the light emitting device 10 maybe picked up or mounted stably to prevent cracks which may otherwise begenerated in the light emitting device 10.

A total area of the four connection tips 55 b may be, for example, about0.8% as compared with the planar area of the light emitting device 10according to the exemplary embodiment.

Table 1 shows a comparison between area ratios of the connection tips 55b and success probabilities of picking up the light emitting device 10depending on areas of the connection tips 55 b formed in the lightemitting device 10 as described above.

TABLE 1 Area ratio (Based on the area of the Pickup success lightemitting rate of the light device) emitting device  1st Modified Example1.26% Not less than 50%  2nd Modified Example 0.65% Good  3rd ModifiedExample 1.22% Not less than 50%  4th Modified Example 1.22% Not lessthan 50%  5th Modified Example 2.71% Bad  6th Modified Example 2.71% Bad 7th Modified Example 0.58% Good  8th Modified Example 2.76% Bad  9thModified Example 1.68% Less than 50% 10th Modified Example 1.26% Notless than 50% 11th Modified Example 1.26% About 50% 12th ModifiedExample 1.92% Less than 50% 13th Modified Example 1.61% Less than 50%14th Modified Example 0.49% Good 15th Modified Example  0.8% Good

Through the first to fifteenth modified examples, it is confirmed thatthe pick-up success rate of the light emitting devices 10 issatisfactory when the area ratio of the connection tips 55 b is, forexample, about 1.2% or less as compared with the planar area of thelight emitting device 10.

FIG. 10 is a schematic cross-sectional view illustrating a unit pixel100 a according to another exemplary embodiment.

Referring to FIG. 10 , the unit pixel 100 a according to the illustratedexemplary embodiment may be substantially similar to the unit pixel 100described with reference to FIGS. 3A and 3B, except that the bumps 133a, 133 b, 133 c, and 133 d are omitted.

A protection layer 131 has openings 131 a exposing connection layers 129a, 129 b, 129 c, and 129 d. The openings 131 a are disposed tocorrespond to the locations of the bumps 133 a, 133 b, 133 c, and 133 dof the unit pixel 100 described with reference to FIGS. 3A and 3B.

As the bumps shown in FIGS. 3A and 3B are omitted in the illustratedexemplary embodiment, a thickness of the protection layer 131 is about ½or less of a thickness of the protection layer 131 in the unit pixel 100of FIGS. 3A and 3B, and, further, may be about ⅓ or less. For example,the thickness of the protection layer 131 in the unit pixel 100 of FIGS.3A and 3B may be about 45 μm, and the thickness of the protection layer131 according to the illustrated exemplary embodiment may be about 15μm.

FIG. 11 is a schematic cross-sectional view illustrating a pixel module1000 a according to another exemplary embodiment. Hereinafter, the pixelmodule 1000 a in which the unit pixels 100 a of FIG. 10 are mounted willbe described.

Referring to FIG. 11 , the pixel module 1000 a according to theillustrated exemplary embodiment is generally similar to the pixelmodule 1000 described with reference to FIGS. 4A and 4B, except thatbonding material 1005 fills openings 131 a of a protection layer 131because the unit pixel 100 a does not have bumps. The bonding material1005 may completely fill the openings 131 a of the protection layer 131,or may partially fill the openings 131 a of the protection layer 131.When the bonding material 1005 partially fills the openings 131 a of theprotection layer 131, a cavity may be formed in the openings 131 a.

A displaying apparatus 10000 may be provided by arranging a plurality ofpixel modules 1000 a on a panel substrate 2100.

Although certain exemplary embodiments and implementations have beendescribed herein, other embodiments and modifications will be apparentfrom this description. Accordingly, the inventive concepts are notlimited to such embodiments, but rather to the broader scope of theappended claims and various obvious modifications and equivalentarrangements as would be apparent to a person of ordinary skill in theart.

What is claimed is:
 1. A display apparatus, comprising: a panelsubstrate; and a pixel module disposed on the panel substrate, the pixelmodule including: a circuit board, and a plurality of unit pixelsdisposed on the circuit board, wherein: each of the unit pixels includesa plurality of light emitting devices longitudinally extending along afirst direction and arranged on the circuit board, each of the lightemitting devices comprises: a substrate; a light emitting layerincluding a first conductivity type semiconductor layer, a secondconductivity type semiconductor layer, and an active layer interposedbetween the first and second conductivity type semiconductor layers; afirst connection layer electrically connected to the first conductivitytype semiconductor layer; a second connection layer electricallyconnected to the second conductivity type semiconductor layer; and astep adjustment layer disposed between the circuit board and the lightemitting layer and covering a portion of the light emitting device, andthe light emitting devices in the unit pixels are arranged in a seconddirection crossing the first direction.
 2. The display apparatus ofclaim 1, wherein: the light emitting devices include at least threelight emitting devices that are each configured to emit light having apeak wavelength that is different with respect to the other of the atleast three light emitting devices; and the at least three lightemitting devices are arranged along a line.
 3. The display apparatus ofclaim 1, wherein the light emitting devices are configured to emit redlight, green light, and blue light, respectively.
 4. The displayapparatus of claim 1, further comprising a light blocking layer disposedbetween at least two of the light emitting devices.
 5. The displayapparatus of claim 4, wherein the light blocking layer has an openregion to transmit light generated in at least one of the two lightemitting devices.
 6. The display apparatus of claim 1, furthercomprising a cover layer covering the plurality of unit pixels.
 7. Thedisplay apparatus of claim 6, further comprising a light blocking layerdisposed between the cover layer and the circuit board.
 8. The displayapparatus of claim 7, wherein the light blocking layer has an openregion to transmit light generated in at least one of the light emittingdevices.
 9. The display apparatus of claim 1, further comprising aprotection layer covering the step adjustment layer, the firstconnection layer, and the second connection layer, wherein theprotection layer has a first opening formed on the first connectionlayer and a second opening formed on the second connection layer. 10.The display apparatus of claim 9, further comprising: a first bumpdisposed in the first opening; and a second bump disposed in the secondopening, wherein: the first bump is electrically connected to the firstconnection layer, and the second bump is electrically connected to thesecond connection layer.
 11. A display module, comprising: a substrate;a cover layer disposed on the substrate; and a pixel module arranged onthe substrate, the pixel module including a plurality of unit pixelsdisposed on the substrate, wherein: each of the unit pixels includes aplurality of light emitting devices longitudinally extending along afirst direction, each of the light emitting devices comprises: a lightemitting layer including a first conductivity type semiconductor layer,a second conductivity type semiconductor layer, and an active layerinterposed between the first and second conductivity type semiconductorlayers; a first connection layer electrically connected to the firstconductivity type semiconductor layer; a second connection layerelectrically connected to the second conductivity type semiconductorlayer; and a step adjustment layer disposed between the substrate andthe light emitting layer, the cover layer is disposed between at leasttwo of the light emitting devices, and the light emitting devices in theunit pixels are arranged in a second direction crossing the firstdirection.
 12. The display module of claim 11, wherein: the lightemitting devices include at least three light emitting devices that areeach configured to emit light having a peak wavelength that is differentwith respect to the other of the at least three light emitting devices;and the at least three light emitting devices are arranged along a line.13. The display module of claim 11, wherein the light emitting devicesare configured to emit red light, green light, and blue light,respectively.
 14. The display module of claim 11, further comprising anadhesive layer disposed on the substrate.
 15. The display module ofclaim 11, further comprising a light blocking layer disposed between thecover layer and the substrate.
 16. The display module of claim 11,further comprising a protection layer covering the step adjustmentlayer, the first connection layer, and the second connection layer,wherein the protection layer has a first opening formed on the firstconnection layer and a second opening formed on the second connectionlayer.
 17. The display module of claim 16, further comprising: a firstbump disposed in the first opening; and a second bump disposed in thesecond opening, wherein: the first bump is electrically connected to thefirst connection layer, and the second bump is electrically connected tothe second connection layer.
 18. A display module, comprising: asubstrate; and a pixel module arranged on the substrate, and the pixelmodule including: a plurality of unit pixels disposed on the substrate,and a cover layer covering the unit pixels, wherein: each of the unitpixels includes a plurality of light emitting devices longitudinallyextending along a first direction and arranged on the substrate, each ofthe light emitting devices comprises: a light emitting layer including afirst conductivity type semiconductor layer, a second conductivity typesemiconductor layer, and an active layer interposed between the firstand second conductivity type semiconductor layers; a first connectionlayer electrically connected to the first conductivity typesemiconductor layer; a second connection layer electrically connected tothe second conductivity type semiconductor layer; and an adhesive layerdisposed on the substrate and covering a region of the light emittinglayer, and the light emitting devices in the unit pixels are arranged ina second direction crossing the first direction.
 19. The display moduleof claim 18, further comprising a light blocking layer disposed betweenat least two of the light emitting devices, wherein the light blockinglayer has an opening to transmit light generated in at least one of thetwo light emitting devices.
 20. The display module of claim 18, whereinthe light emitting devices are configured to emit red light, greenlight, and blue light, respectively.